Macromolecules containing phosphorylcholine groups have been developed as biocompatible materials. Polymers having phosphorylcholine groups have been synthesized mainly as follows: acryl type monomers mainly having hydroxyl groups and 2-chloro-1,3,2-dioxaphosphorane-2-oxide are brought into reaction and then trimethylamine is used to turn the reaction product into quaternary ammonium to synthesize monomers having a phosphorylcholine structure, which are then polymerized.
However, due to the monomer solubility issues when introducing the hydrophobic groups, this method requires the use of an organic solvent known as a chain transfer catalyst such as methanol, ethanol, and chloroform as a polymerization solvent, which makes it difficult to produce high molecular weight polymers. Also, the monomer synthesis reaction has to be conducted under strictly anhydrous conditions, which complicates the technique.
In addition the conventional manufacturing method that polymerizes monomers having phosphorylcholine on side chains has a problem in that the steric hindrance of the phosphorylcholine group reduces the polymerization yield or makes it impossible to obtain the desired polymer.
In view of the description above, the inventors conducted earnest research on the manufacturing method of the phosphorylcholine group-containing polymer, and completed the present invention by discovering that polysaccharides having the phosphorylcholine structure can be obtained easily and with a high versatility by reacting a compound containing phosphorylcholine groups with a polysaccharide having a functional group that reacts with this compound, which leads to a macromolecular reaction in the side chains of the polymer.